NAME

dup2 − duplicate an open file descriptor

SYNOPSIS

int dup2 (fildes, fildes2)
int fildes, fildes2;

DESCRIPTION

fildes is a file descriptor referring to an open file, and fildes2 is a non-negative integer less than NOFILES. dup2 causes fildes2 to refer to the same file as fildes. If fildes2 already referred to an open file, it is closed first. 

dup2 fails if one or more of the following are true:

[EBADF] fildes is not a valid open file descriptor. 

­[EMFILE] NOFILES file descriptors are currently open. 

SEE ALSO

creat(2), close(2), exec(2), fcntl(2), open(2), pipe(2), lockf(3C). 

DIAGNOSTICS

Upon successful completion a non-negative integer, namely the file descriptor, is returned.  Otherwise, a value of −1 is returned and errno is set to indicate the error. 

March 13, 1992